Shooters Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
36 Posts
Discussion Starter #1 (Edited)
When conicals are fired in a rifled percussion muzzleloader, their base expands and obturates the bore of the barrel.

1) What shape should we expect to see when the round ball exits the muzzle?


2) What shape should we expect to see when the conical exits the muzzle?



Thank you

PS.

This is the last of my questions for at least 2 months.
 

·
Super Moderator
Joined
·
13,448 Posts
Usually I see the shape of the front sight returning to position. Can't see the projectiles at all.

That said, if you have a high speed camera, the answer will depend on the pressure of the load and the hardness of the projectile alloy. If you have too much pressure it may cause serious deformation. It can squash the ball front to back (disastrous for accuracy in a smoothbore, because now you have a shape with irregular air resistance as it tumbles). Too much pressure can blow the skirt open on a hollow base conical bullet, like a Minie Ball, as it exits, and that creates a lot of extra drag. If you don't have enough pressure to cause any deformation, a hollow skirt may not expand to engage rifling. If it is low enough, little to no deformation takes place.
 

·
Registered
Joined
·
36 Posts
Discussion Starter #3
Usually I see the shape of the front sight returning to position. Can't see the projectiles at all.

That said, if you have a high speed camera, the answer will depend on the pressure of the load and the hardness of the projectile alloy. IF you have too much pressure it may cause serious deformation. It can squash the ball front to back (disastrous for accuracy in a smoothbore, because now you have a shape with irregular air resistance as it tumbles). Too much pressure can blow the skirt open on a hollow base conical bullet, like a Minie Ball, as it exits, and that creates a lot of extra drag. If you don't have enough pressure to cause any deformation, a hollow skirt may not expand to engage rifling. If it is low enough, little to no deformation takes place.
Thanks UncleNick!
 

·
Banned
Joined
·
255 Posts
If you can hit something soft/fluffy at long range you can look at the projectile after it stops. Wood shavings, straw, sawdust etc. at 400 yards should not deform the bullet much on impact. You can pour sawdust through a screen to recover the bullet..
 

·
Registered
Joined
·
1,388 Posts
It also makes a difference which way the camera shutter open and closes. If it movesthe same direction as the projectile the projectile will be elongated. If it moves the opposite direction the projectile image will be shortened. If it moves transversely the image will be sloped at the top or conversely at the bottom depending on which way the shutter was moving.
 

·
Super Moderator
Joined
·
13,448 Posts
I don't think the modern digital electronic cameras have shutters, per se. You can look at the display at the back like a TV monitor and when you press the "shutter" button it just captures whatever the sensor array output is at that moment. In a slow exposure it will capture and average a number of rapid interrogations of the array to filter noise, which is how you see a smear if you don't hold them still. The difference between the high speed and standard versions would be the rate of the CCD scan and the speed of the individual pixel sensors in the array. It takes special low capacitance sensors to react quickly, but they've got them. If you've looked at the Kurzzeit videos online, they are all digital electronic high speed captures. Mostly in the half million to one million frame per second range. Kurzzeit makes the cameras.

Film technology is pretty much gone on modern cameras. Even movies are shot with digital electronic cameras now and the output is printed on film only for distribution. Memory is cheaper than film, is reusable, and they director can view what was just shot a moment later to decide what needs to be redone without waiting for the "dailies" and before makeup has even been removed from the actors. Editing is on computer. All faster and cheaper than the old ways of working.

I find that too bad in some ways. I studied Ansel Adam's books when I was younger and learned to mix developers from scratch to help control contrast and use selected anti-fog chemicals and toners to bring black and white prints to neutral color and to use bleaching to clean whites and Kodalith overlays to get maximum blacks. Quite a process. And I still miss the smell of the darkroom and still admire Adam's black and white prints. But it is obsolete.
 
1 - 6 of 6 Posts
Top